The purpose of the proposed research is to understand the neurocognitive processes that underlie human recognition memory. Recognition memory is supported by processes that are sensitive to the general familiarity of information as well as by processes that enable the recollection of specific details (e.g., knowing that a person is familiar and recollecting that she is a doctor). Our recent research suggests that recollection and familiarity can be differentiated by measuring electrical activity in the brain with event-related brain potentials (ERPs): Early (300-500 ms) frontal ERP effects appear to be affected by familiarity, whereas later (400-800 ms) parietal ERP effects appear to be related to recollection. The overarching goal of the proposed research is to use these neurophysiological correlates of recollection and familiarity, in combination with other behavioral and pharmacological methods, to examine several issues that are central to understanding the processes and neural systems involved in recognition memory. This goal will be realized in three specific aims. The first specific aim will focus on understanding the continuous vs. threshold nature of recognition memory processes. The second specific aim will examine whether the parietal old/new effect is sensitive to veridical memory or perceived oldness. The third specific aim will examine the manner in which several distinct processes may contribute to our ability to recognize and/or retrieve associative information from a study episode. The proposed research will further our basic understanding of recognition memory processes by allowing us to establish clear relationships between electrophysiological responses and recognition memory performance while testing critical hypotheses about the nature of recollection and familiarity processes. To clearly understand the manner in which the component processes of recognition memory are selectively impaired by aging, disease, and neurological insult, it is crucial to understand the neural bases of these recognition memory processes. The enhanced knowledge that will result from the proposed research will help with the design of specific interventions to improve memory in each of these different populations, and will pave the way for understanding the manner in which aging, disease, and brain injury can selectively impair, and more importantly, spare memory processes.